Initial experience with Imacor hTEE-guided management of patients following transplant and mechanical circulatory support.

TL;DR: Real-time “hemodynamic” TEE (hTEE) can help provide effective management by direct visualization of cardiac filling and function and help guide hemodynamic management following transplant or MCS.

Abstract: This study reviews an initial experience using a miniaturized transesophageal echocardiography (TEE) probe (ImaCor, Garden City, NY) with 3 patients in whom Imacor hTEE intervention was used as a point-of-care device to manage extracorporeal membrane oxygenation cannula placement, cardiac hemodynamics, and postoperative cardiac pathophysiology. The management of transplant or mechanical circulatory support (MCS) patients is especially challenging: Transplanted hearts pose unique pathophysiological challenges, and MCS significantly alters pressure–volume–flow relationships. Real-time “hemodynamic” TEE (hTEE) can help provide effective management by direct visualization of cardiac filling and function and help guide hemodynamic management. In the authors’ initial experience, hTEE can provide point-of-care management following transplant or MCS.

Summary

Introduction

• The authors reviewed an initial experience using a miniaturized transesophageal echocardiography (TEE) probe (ImaCor, Garden City, NY) with 3 patients in whom Imacor hTEE intervention was used as a point of care device to manage extracorporeal membrane oxygenation cannula placement, cardiac hemodynamics, and post-op cardiac pathophysiology.
• The management of transplant or mechanical circulatory support (MCS) patients is especially challenging: transplanted hearts pose unique pathophysiological challenges, and MCS significantly alters pressure-volume-flow relationships.
• Real-time “hemodynamic” TEE (hTEE) can help provide effective management by direct visualization of cardiac filling and function and help guide hemodynamic management.
• In their initial experience, hTEE can provide point-of-care management following transplant or MCS.

Conflict of Interest

• Other authors has no conflict of interest.
• This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
• Fluid and hemodynamic management, fundamental in critical care, becomes significantly more challenging in transplant patients and patients with mechanical circulatory support.
• These alterations can further limit the utility of standard pressure measurements, both central venous pressure and pulmonary artery pressure.
• TEE would appear to be the ideal tool for hemodynamic assessment and management of critically ill patients 5 , provided that availability and the need for trained personnel and anesthesia can be overcome.

Methods

• The authors reviewed their initial experience with 3 patients in whom the Imacor hTEE system was used as a point-of-care device to manage extracorporeal membrane oxygenation (ECMO) cannula placement, cardiac hemodynamics, and post-op cardiac pathophysiology.
• This study was approved by an institutional review board at Thomas Jefferson University Hospital.

Results

• A 55-year-old female with a history of dilated cardiomyopathy, presented for a heart transplantation evaluation, also known as Case 1.
• Twelve hours later, the Swan-Ganz catheter showed tamponade physiology with equalization of pulmonary artery diastolic pressure (26 mm Hg) and central venous pressure (25 mm Hg) with decreased cardiac index (2.0 L/min/cm 2 ).
• Real time imaging with continuous hTEE demonstrated deteriorating biventricular function to near cardiac standstill .
• Her hemodynamics did not improve despite multiple inotropes and an intra-aortic balloon pump placement.
• The patient developed severe pulmonary edema and was transferred to their institution for VA ECMO placement.

Discussion

• These 3 cases illustrate how Imacor hTEE intervention was used as a point of care device to manage extracorporeal membrane oxygenation (ECMO) cannula placement, cardiac hemodynamics, and post-op cardiac pathophysiology.
• Weaning from ECMO requires recovery of either RV and/or LV cardiac function.
• The hTEE probe provides real time images of the heart, allowing the intensivist to determine if the preload is appropriate and cardiac function is adequate and intervene rapidly if necessary.
• Heart transplant patient with prolonged ischemic time and elevated recipient pulmonary vascular resistance often develop RV failure, which can progress to biventricular failure.
• Sharply reduced flow is usually related to the volume status of the patient, and resolved by administering volume.

Conclusion

• The authors found hTEE helped guide point-of-care management of patients post- transplant or with mechanical circulatory support accurately and acutely.
• The International Society of Heart and Lung Transplantation Guidelines for the care of heart transplant recipients.
• A systematic review of the literature and the tale of seven mares.
• B. Adjustment of cannula (indicated by ellipse, cannula visible as parallel lines) and ECMO RPM displaced and released the thrombus (indicated by arrow) from the catheter opening – this was further confirmed by resumption of ECMO flow at 4.5 L/min.

Figures

Figure 1. A. Biventricular failure at the time of ECMO insertion. B. RV function improved with 3 weeks of ECMO support although the LV remained dilated. LV: left ventricle; RV: right ventricle. Line in the RV indicates RV dimension. Please note the RV dimension is smaller in Figure 1B than 1A, indicating the recovery of RV function.

Full text

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1
As submitted to:
ICU Director
And later published as:
Initial Experience with Imacor hTEE-guided management of
patients following Transplant and Mechanical Circulatory
Support.
August 22, 2012,
doi:10.1177/1944451612456703
Abstract
We reviewed an initial experience using a miniaturized transesophageal
echocardiography (TEE) probe (ImaCor, Garden City, NY) with 3 patients in whom
Imacor hTEE intervention was used as a point of care device to manage extracorporeal
membrane oxygenation cannula placement, cardiac hemodynamics, and post-op cardiac
pathophysiology. The management of transplant or mechanical circulatory support
(MCS) patients is especially challenging: transplanted hearts pose unique
pathophysiological challenges, and MCS significantly alters pressure-volume-flow
relationships. Real-time “hemodynamic” TEE (hTEE) can help provide effective
management by direct visualization of cardiac filling and function and help guide
hemodynamic management. In our initial experience, hTEE can provide point-of-care
management following transplant or MCS. (Word count of abstract: 105)

2
Keywords: ECMO, TEE, mechanical circulatory support, hemodynamics
Conflict of Interest
XXXX is an employee and stockholder in ImaCor. Other authors has no conflict of
interest. This research received no specific grant from any funding agency in the public,
commercial, or not-for-profit sectors.

3
Introduction
Fluid and hemodynamic management, fundamental in critical care, becomes
significantly more challenging in transplant patients and patients with mechanical
circulatory support. Transplanted hearts pose unique pathophysiological challenges
1, 2
,
and mechanical support significantly alters pressure-volume-flow relationships. These
alterations can further limit the utility of standard pressure measurements, both central
venous pressure and pulmonary artery pressure. Central venous pressure has been shown
to have a poor relationship with volume status.
3
The Swan-Ganz catheter provides
indirect measurements that can be difficult to interpret; moreover altered pressure-
volume-flow relationships. Transesophageal echocardiography (TEE) directly visualizes
the heart, allowing accurate assessment of cardiac function and volume status with other
parameters.
4
Cardiac anesthesiologists rely on TEE images to make hemodynamic
assessments and interventions in the cardiac operating room. TEE would appear to be the
ideal tool for hemodynamic assessment and management of critically ill patients
5
,
provided that availability and the need for trained personnel and anesthesia can be
overcome. An editorial called for a TEE probe which could remain indwelling 48 hours
in critically ill patients.
6
To address these issues,
a miniaturized TEE probe (hTEE probe, ImaCor, Garden
City, NY
) with a diameter of 5.5 mm was developed to provide hemodynamic
management and assessment in critical care to aid in assessment of volume status and
cardiac function with other parameters. The hTEE probe was cleared by the FDA to
remain indwelling up to 72 hours.
The hTEE probe has 15 cm of penetration at 6.67

4
MHz (B-mode) and can obtain the images of left and right ventricular function and
volume status.
7
Methods
We reviewed our initial experience with 3 patients in whom the Imacor hTEE system was
used as a point-of-care device to manage extracorporeal membrane oxygenation (ECMO)
cannula placement, cardiac hemodynamics, and post-op cardiac pathophysiology. This
study was approved by an institutional review board at Thomas Jefferson University
Hospital.
Results
Case 1: A 55-year-old female with a history of dilated cardiomyopathy, presented for a
heart transplantation evaluation. She quickly decompensated into multiple organ failure
despite significant inotropic support. It was decided that emergent Veno-arterial ECMO
placement for biventricular support was necessary (Figure 1A). Over 3 weeks of VA
ECMO support, the patient was deemed not a candidate for heart transplantation.
Although the patient remained eligible for a left ventricular (LV) assist device, right
ventricular (RV) function had not been evaluated prior to decompensation.
A weaning protocol was initiated with hTEE for direct visualization of cardiac
function to assess RV function. Over four hours, ECMO flows were decreased, and
volume and dobutamine were administered. hTEE showed that the right heart was
adequate to tolerate a bridge to LVAD (Figure 1B). The patient was successfully weaned
off ECMO and bridged to an LVAD as predicted.
Case 2: A 47-year-old male with a Heartmate II LVAD (Thoratec,
Pleasanton, CA)
underwent orthotropic heart transplantation. Postoperatively, the patient required

Frequently asked questions

Q1. What have the authors contributed in "Initial experience with imacor htee-guided management of patients following transplant and mechanical circulatory support" ?

The authors reviewed an initial experience using a miniaturized transesophageal echocardiography ( TEE ) probe ( ImaCor, Garden City, NY ) with 3 patients in whom Imacor hTEE intervention was used as a point of care device to manage extracorporeal membrane oxygenation cannula placement, cardiac hemodynamics, and post-op cardiac pathophysiology. 

Q2. What is the common cause of a heart transplant?

Heart transplant patient with prolonged ischemic time and elevated recipient pulmonary vascular resistance often develop RV failure, which can progress to biventricular failure. 

Q3. What is the reason for the ECMO failure?

in the presence of escalating vasopressor support secondary to systemic vasoplegia syndrome, normal pressure may not yield normal perfusion. 

Q4. What is the role of the hTEE probe in critical care?

Fluid and hemodynamic management, fundamental in critical care, becomessignificantly more challenging in transplant patients and patients with mechanical circulatory support. 

Q5. What is the way to monitor a heart?

ECMO weaning requires ongoing observation of cardiac function through major circulatory changes which are visualized by real time continuous hTEE. 

Q6. What is the role of hTEE in ECMO?

The management of transplant or mechanical circulatory support patients is especially challenging: transplanted hearts pose unique pathophysiological challenges, and mechanical circulatory support significantly alters pressure-volume-flow relationships. 

Q7. What is the main reason for the failure of the heart?

Primary biventricular failure post-transplantation, as seen in Case 2, may berelated to poor myocardial preservation of the donor, prolonged ischemic time, residual pulmonary hypertension, and decreased compliance of the lungs post cardiopulmonary bypass. 

Q8. What is the way to manage a heart transplant?

Real-time “hemodynamic” TEE (hTEE) can help provide effective management by direct visualization of cardiac filling and function and help guide hemodynamic management. 

Q9. What is the role of the TEE probe in critical care?

TEE would appear to be the ideal tool for hemodynamic assessment and management of critically ill patients 5 , provided that availability and the need for trained personnel and anesthesia can be overcome. 

Q10. What is the way to evaluate the circulation of the heart?

Placement of a Swan-Ganz catheter (SGC)venous gas analysis would also be useful to evaluate the circulation and function of the heart; however, the lag between the sampling the blood and results may makes ongoing real-time adjustments difficult. 

Q11. What is the cause of the near ventricular standstill?

This lack of normal perfusion was the apparent cause of near ventricular standstill detected by hTEE, a condition which if not managed by central ECMO might otherwise have led to cardiac arrest. 

Q12. What is the purpose of the hTEE probe?

The hTEE probe provides real time images of the heart, allowing the intensivist to determine if the preload is appropriate and cardiac function is adequate and intervene rapidly if necessary. 

Q13. What is the way to monitor the heart?

If ventricular recovery is questionable, hTEE probe can be left in the patient for continuous monitoring of the cardiac function, potentially saving the cost of taking the patient to the operating room.